They Shoot Pictures, Don’t They? is a very cool site that aggregates as many top movie lists as they can. As of the time I posted this, I was at 32% of their 21st Century’s 250 Most Acclaimed Films list. Good list. Worth more effort.
I should note that I don’t do these film lists out of a desire to keep score; it’s because I want to understand movies better, and seeing more great movies helps me with that.